When Ford engineers embarked on the EcoBoost program six years ago, they plucked the 3.5L Duratec V-6 out of the corporate engine lineup to use as a starting point. The naturally aspirated Duratec is plenty capable in its own right, putting out 265 hp and 250 lb-ft. Despite the extra 100 hp that the EcoBoost was projected to produce, only minor revisions were necessary. The EcoBoost retains the Duratec's 3.64x3.41-inch bore and stroke dimensions, but the block has been fortified with additional reinforcement ribs. Likewise, Ford beefed up the crank and rods by using an alloy with greater nickel and chromium content. The pistons, while cast, feature a low-friction coating on their skirts, and are cooled by oil squirters positioned in the crankcase. Furthermore, the cylinder heads were fitted with 1.456/1.220-inch Inconel valves, and modified to facilitate fitment of the high-pressure fuel injectors. In addition to a slight drop in compression ratio, multi-layer steel head gaskets have been added to help seal the chambers under boost.